You know what’s kind of awesome? Understanding the economic development level of virtually every country on earth becomes much easier as soon as you realize the massive correlation between per capita and IQ–and it gets even better if you focus on verbal IQ or “smart fraction” vebal IQs:

La Griffe du Lion has a lot of great articles explaining phenomena via math, so if you haven’t read them already, I strongly recommend that you do.

One wonders what this data would look like if we looked backwards, at per capita GDP in, say, the 15 to 1800s.

I really hope I can find a better graph (this one’s from Wikimedia)

Also from Wikimedia

According to the Guardian article about the paper British Economic Growth 1270-1870, “estimates that per capita income in England in the late middle ages was about $1,000 or £634 a year when compared with currency values in 1990.

“According to the World Bank, countries which had a per capita income of less than $1,000 last year included Ghana ($700), Cambodia ($650), Tanzania ($500), Ethiopia ($300) and Burundi ($150), while in India – one of the BRIC emerging economies – the gross income per capita stands only just above medieval levels at $1,180.”

“The %GDP of Western Europe in the chart is the region in Europe that includes the following modern countries – UK, France, Germany, Italy, Belgium, Switzerland, Denmark, Finland, Sweden, Norway, Netherlands, Portugal, Spain and other smaller states in the Western part of Europe.

The %GDP of Middle East in the chart is the region in West Asia and Northeast Africa that includes the following modern countries – Egypt, Israel, Palestinian Territories, Lebanon, Syria, Turkey, Jordan, Saudi Arabia, Qatar, Bahrain, Kuwait, UAE, Oman, Yemen, Iran, Iraq and other regions in the Arabian region.”

The problem with doing the graph this way is that it doesn’t control for population growth. Obviously the US expanded greatly in population between 1700 and 1950, crushing the rest of the world’s GDP by comparison, without anyone else necessarily getting any poorer. It would be nice if the graph included Africa, because I wonder how things like Mansa Musa’s gold mines would show up.

At any rate, here is my impression, which this graph basically seems to back up:

Around the time of the Romans, “Europe” and the Middle East had similar levels of development, integration into global economy, etc. The fall of the Roman Empire coincided with the Middle East pulling ahead in math, science, and nice-looking buildings.

Meanwhile, India and China were doing quite well for themselves, though it’s not clear from the graph how much of that is population. I would not be surprised to find similar numbers for per capita GDP at that time, though.

Then around 1000, Europe starts to improve while the Middle East falls behind and stays there. I suspect this is in part because cousin marriage became more common in the Middle East between 0 and 1000 while simultaneously becoming less common in Europe, and because the Middle East probably didn’t have much arable land left to expand into and so population couldn’t increase very much, whereas the Germans started their big eastward migration about then, (The Ostsiedlung–goodness, it took me a while to figure out how that’s spelled.) increasing the number of Europeans in our cohort and spurring growth.

(BTW…

Click for the bigger version )

India, meanwhile, went downhill for a long time, for I have no idea why reasons. China was doing great until quite recently, when it apparently went capootie. Why? I don’t know, but I think part of the effect is just Europe (and the US) suddenly pulling ahead, making China look less significant by comparison.

So. Extrapolating backwards from what we know about the correlation between GDP and verbal IQ, I suspect Western Europe experienced a massive increase in IQ between 1000 and 1900.

A large chunk of this increase was probably driven by the German eastward expansion, a rather major migration you’ve probably never heard of. (As HBD Chick says, “from a sociobiological point-of-view, probably the most underappreciated event in recent western european history. that and the reconquest of spain.”) Another large chunk was probably driven by various cultural factors unique to manorialism and Christianity.

Windmills began popping up in Western Europe in the late 1100s (given that they seem to have started in France, England, and Flanders, rather than in areas geographically closer to the Middle East, it seems unlikely that the European windmills were inspired by earlier Middle Eastern windmills, but were instead a fairly independent invention.

Watermills were an earlier invention–the Classical Romans and Greeks had them. The Chinese and Middle Easterners had them, too, at that time. I don’t know how many mills they all had, but Europeans really took to them:

“At the time of the compilation of the Domesday Book (1086), there were 5,624 watermills in England alone, only 2% of which have not been located by modern archeological surveys. Later research estimates a less conservative number of 6,082, and it has been pointed out that this should be considered a minimum as the northern reaches of England were never properly recorded. In 1300, this number had risen to between 10,000 and 15,000. [Bold mine.]By the early 7th century, watermills were well established in Ireland, and began to spread from the former territory of the empire into the non-romanized parts of Germany a century later. Ship mills and tide mill were introduced in the 6th century.” (Wikipedia page on Watermills.)

In short, by the 1300s, Europe was well on its way toward industrialization.

IMO, these things combined to produce a land where the clever could get ahead and have more children than the non-clever, where those who could figure out a new use or more efficient milling design could profit.

““‘By 1200 Western Europe has a GDP per capita higher than most parts of the world, but (with two exceptions) by 1500 this number stops increasing. In both data sets the two exceptions are Netherlands and Great Britain. These North Sea economies experienced sustained GDP per capita growth for six straight centuries. The North Sea begins to diverge from the rest of Europe long before the “West” begins its more famous split from “the rest”. [W]e can pin point the beginning of this “little divergence” with greater detail. In 1348 Holland’s GDP per capita was $876. England’s was $777. In less than 60 years time Holland’s jumps to $1,245 and England’s to 1090. The North Sea’s revolutionary divergence started at this time.’”

The result, I suspect, was an increase in average IQs of about 10 to 15 points–perhaps 20 points in specific sub-groups, eg Ashkenazi Jews–with an overall widening of the spread toward the top end.

[…] The Ostsiedlung, for example, selected for German citizens who were well-disciplined, hard working, good planners, and probably quick to defend their land holdings from others. Overall, Germans descended from the […]

You should check out Farewell to Alms by Clark. Pre-1800 the world was Malthusian, so GDP/capita was mostly determined by the demographic regime; therefore you’d have to back out that effect before trying to estimate IQ.